Reverse Single Crochet aka Crab Stitch ~ This stitch is worked from left to right (or opposite direction) than you normally crochet.

With right side of project facing you Chain 1, * insert hook into next stitch to right, yarn over and pull through, (2 loops on hook), yarn over and pull through both loops *. Continue working * to * until you have reached the end of project. Slip stitch into first chain 1 and fasten off, weave in ends.

FHDC – (Foundation Half Double Crochet) Chain 2, yarn over, insert hook into first chain (2nd from the hook), yarn over, pull up through the first loop on the hook (this is your first chain loop). With 3 loops on hook, yarn over, pull through 3. * Yarn over, insert your hook into the first chain loop, yarn over, pull up a loop (this is your second chain loop), yarn over, pull through 3. 2 fhdc completed. Repeat from * until you reach the desired number of fhdc.

Row 1: Chain 1, sc in the same stitch,
work (hdc, dc, tr, tr, dc, hdc, sc) over the next 7 stitches,
* work (sc, hdc, dc, tr, tr, dc, hdc, sc) over the next 8 stitches, * repeat from * to * across,
ending with a sc in the last stitch. Turn (4 waves)

Fasten off color A; attach Color B

Row 2: Chain 1, trc in the same stitch as the chain 1
work (dc, hdc, sc) over next 3 stitches,
* work (sc, hdc, dc, tr, tr, dc, hdc, sc) over the next 8 stitches, * repeat from * to * across,
ending with a tr in the last stitch. Turn (3 waves, ½ wave on each end = 4 waves)

Fasten off color B; attach Color A

Rows 4–20: Repeat Rows 1 and 2 (changing colors after each row)

Fasten off.

Using both colors, Attach both colors in a corner space

Round 1: Chain 2, hdc in the same corner space,
* hdc in each stitch across, work 3 hdc in the next corner space, * repeat from * to * around,
ending with a hdc in the beginning corner space;
join with a slip stitch in the top of the first hdc.